1. Field of the Invention
The present invention relates to a method and apparatus for identifying defective equipment causing defective products, and more particularly, to a method and apparatus for identifying which piece of equipment needs to be fixed among pieces of equipment through which defective products of a defective sample passed by using a defect map of the entire defective sample composed of the defective products.
2. Description of the Related Art
When a product produced after passing through a plurality of pieces of equipment is defective, it is not easy to find which piece of equipment caused a defect in the product. This is because even if one piece of equipment is defective, it does not always cause a defect. In addition, defective products may have been produced after passing through different processes and pieces of equipment.
A product may be divided into a plurality of cells, and whether the product is defective may be determined on a cell-by-cell basis. In addition, a defective sample may consist of products, each having one or more defective cells. In this case, a sample defect map showing the number of defective cells in each cell position of the defective sample is generated, and a defective piece of equipment is searched for by inspecting the sample defect map with the naked eye. For example, by using an equipment defect map for each piece of equipment as a reference value, an analysis engineer may inspect the sample defect map and the equipment defect map with the naked eye. That is, the analysis engineer may find a defective piece of equipment by evaluating the similarity between the sample defect map and the equipment defect map. In this conventional method, however, a defective piece of equipment is determined not based on objective indices but based on the analysis engineer's subjective experience. Therefore, targets of analysis and the analysis result greatly vary according to the proficiency of the analysis engineer.